Emergent extraction technologies to valorize fruit and vegetable residues

Fruits and vegetables residues are very rich in bioactive compounds and other valuable components. Until a few decades ago, these residues were considered neither a cost nor a benefit resulting in a significant negative impact to the environment, or being applied as animal feed, brought to landfills or sent to composting sites. Today, these residues can be used as a source of nutritionally and pharmacologically functional ingredients, with important applications in food, pharmaceutical, and cosmetic sectors. The extraction of these compounds is usually done through conventional thermal methods, since they are easy to perform and cheap to operate. However, they present several constraints mainly due to thermo-sensible compounds degradation and environment pollution concerns associated with solvents required. Recently, new nonthermal and mild-thermal extraction technologies have been in development to assist the extraction process of high-value compounds. High pressure, ultrasounds, electro, and supercritical fluids based technologies present important advantages when compared with traditional methods since they are considered environmentally friendly, use lower amounts of organic solvents, reduce the extraction time and energy consumption, leading to higher yields and final high quality extracts. However, much more research is needed to improve the understanding of the extraction mechanisms, design, and scale-up of these systems for a potential industrial application. This chapter provides a critical comparison between some emergent methods (high pressure, ultrasounds, electro, and supercritical fluids based technologies) for bioactive compounds extraction from fruits and vegetables residues. In addition, since the main parameters influencing the extraction yields are also discussed, this chapter can be useful for the selection of an appropriate extraction method.